Generally, poles are long thin pieces that may be used for various purposes, such as walking sticks for hiking or trekking or support poles for tents.
Such poles are typically used by aged people, physically handicapped people, hikers and trekkers. Further, poles may be used as a symbol of dignity or for self-protection by some people. Thus, such poles may be called walking sticks, staffs or canes.
In recent years, the structures of poles have been developed such that the poles comprise a plurality of assemblable unit shafts instead of an integrated single shaft having a fixed length. Thus, the assemblable poles proposed in recent years can be conveniently stored when not used and the lengths thereof can be easily adjusted as desired.
The conventional poles having the assemblable structures are configured to realize locking between neighboring unit shafts thereof on one surface (that is, one surface locking), so that the poles can somewhat efficiently resist compressive force. However, when tensile force is applied to the pole by pulling two locked unit shafts from each other in opposite directions, both the frictional force and the locking strength between the two locked unit shafts are reduced, so that slippage may occur between the two locked unit shafts and the locked state between the two unit shafts may be released, thus sometimes subjecting users to safety hazards.